Congenital heart disease (CHD) ranges from benign lesions to life-threatening structural abnormalities. While benign lesions may resolve without intervention, severe structural lesions require complex pediatric cardiac surgery. The reconstruction of the aortic arch in children is a complex repair in which perioperative bleeding i a significant, important and frequent complication. Moderate to severe Congenital Heart Disease (CHD) occurs in about 6/1,000 live births. Severe structural lesions that require complex pediatric surgeries have been reported as about 1/1,000 of live births; too many of these children die as a result of perioperative bleeding and the lack of more effective methods to stop bleeding. The reconstruction of the aortic arch in children with severe congenital heart disease often requires transection of the great vessels, significant augmentation, and then suture repair using very small caliber sutures placed extremely close together to ensure repair integrity. However, due to the complex nature of the repair, the anatomy of the neonatal arch, and the anti-coagulation regimen that is required during the cardio-pulmonary bypass, perioperative bleeding is a significant, important and frequent complication. There is a critical, unmet clinical need for an effective method to effect perioperative hemostasis in such patients. High Intensity Focused Ultrasound (HIFU) provides a novel approach for treating perioperative bleeding. HIFU has been demonstrated qualitatively to effectively induce hemostasis. Our overarching research objective is to mitigate the effects of perioperative bleeding in surgically reconstructed great vessels, thus reducing the perinatal morbidity and mortality associated with surgical procedures. The objectives of this proposal is to establish the feasibility and required parameters such that HIFU can be used safely and effectively to mitigate perioperative bleeding (Aim 1), develop a clinical hand-held HIFU system for treating perioperative bleeding (Aim 2), and conduct in vitro and ex vivo experiments in preparations for Phase II studies in an animal model (Aim 3). This collaboration brings together acoustics and instrumentation expertise at BioDesign Research & Development, acoustic bioeffects expertise at the University of Washington, and pediatric surgeons at Seattle's Children's Hospital to develop a device for mitigating perioperative bleeding of surgically reconstructed neonatal great vessels. This Phase I application proposed to conduct the necessary safety and efficacy studies to develop an indication specific device. Phase II of this project will be to evaluate the device in acute and survival animal models. We project Phase II would require approximately 1 million dollars to produce a device ready for clinical evaluation.